1 Answer

When a substance acts as an oxidizing agent, it is reduced and the oxidation number (O.N.) of one of its element decreases. Therefore, a substance cannot acts as an oxidizing agent when it reaches the minimum O.N.

When a substance acts as an reducing agent, it is oxidized and the O.N. of one of its element increases. Therefore, a substance cannot acts as an oxidizing agent when it reaches the maximum O.N.

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1. The answer is c.

a. is incorrect.

MnO4-(aq)/H+ can act as an oxidizing agent because MnO4- (O.N. of Mn = +7) can be reduced to Mn2+ (O.N. of Mn = +2).

b. is incorrect.

Fe3+(aq) can act as an oxidizing agent because Fe3+ (O.N. of Fe = +3) can be reduced to Fe2+ (O.N. of Fe = +2).

c. is correct.

Zn(s) cannot act as an oxidizing agent because Zn cannot be reduced as its O.N. (0) is the minimum.

d. is incorrect.

Cl2(g) can act as an oxidizing agent because Cl2 (O.N. of Cl = 0) can be reduced to Cl- (O.N. of Cl = -1).

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2.) The answer is d.

a. is incorrect.

SO32-(aq) can act as a reducing agent because SO32-(O.N. of S = +4) can be oxidized to SO42-(O.N. of S = =6).

b. is incorrect.

I-(aq) can act as a reducing agent because I- (O.N. of I = -1) can be oxidized to I2 (O.N. of I = 0).

c. is incorrect.

Fe2+(aq) can act as a reducing agent because Fe2+ (O.N. of Fe = +2) can be oxidized to Fe3+ (O.N. of Fe = +3).

d. is correct.

Cr2O72-(aq) cannot act as a reducing agent because Cr2O72- cannot be oxidized as the O.N. of Cr (+6) is the maximum.